Radio resource signaling during network congestion in a mobile wireless device

ABSTRACT

A method for radio link control in a mobile wireless communication device The mobile wireless device transmits a sequence of service requests to establish radio resources with a wireless communication network for a data packet in a pending data buffer. When no radio resources are allocated in response to the transmitted sequence of service requests, the mobile wireless device sets a minimum threshold for the pending data buffer, discards all pending data packets above the minimum threshold and discards the oldest pending data packet. The mobile wireless device repeats transmitting and discarding until a radio resource is allocated or the pending data packet buffer is empty. A retry interval between successive service requests is increased after transmitting each sequence of service requests until reaching a maximum retry interval value.

CROSS-REFERENCE TO RELATED APPLICATIONS

This patent application takes priority under 35 U.S.C. 119(e) to U.S.Provisional Patent Application Ser. No. 61/362,662 entitled, “METHOD ANDAPPARATUS FOR RADIO RESOURCE SIGNALING DURING NETWORK CONGESTION IN AMOBILE WIRELESS DEVICE” by Shiva et al. filed Jul. 8, 2010 which isincorporated by reference herein in its entirety for all purposes.

TECHNICAL FIELD

The described embodiments relate generally to wireless mobilecommunications. More particularly, a method and apparatus is describedfor radio resource signaling during periods of radio access networkcongestion in a mobile wireless communication device.

BACKGROUND OF THE INVENTION

Mobile wireless communication devices, such as a cellular telephone or awireless personal digital assistant, can provide a wide variety ofcommunication services including, for example, voice communication, textmessaging, internet browsing, and electronic mail. Mobile wirelesscommunication devices can operate in a wireless communication network ofoverlapping “cells”, each cell providing a geographic area of wirelesssignal coverage that extends from a radio network subsystem (RNS)located in the cell. The radio network subsystem can include a basetransceiver station (BTS) in a Global System for Communications (GSM)network or a Node B in a Universal Mobile Telecommunications System(UMTS) network. Whether idle or actively connected, a mobile wirelesscommunication device can be associated with a “serving” cell in awireless communication network and be aware of neighbor cells to whichthe mobile wireless communication device can also associate.

Mobile wireless communication devices can support both voice and dataconnections, in some cases simultaneously, through radio resourcesallocated by the radio network subsystem for a radio access portion ofthe wireless communication network. The voice and data connections canalso include paths through circuit switched and/or packet switcheddomains of a core network that interconnects the mobile wirelesscommunication device to a public switched telephone network (PSTN)and/or a public data network (PDN). In order for the data connection toroute packets, also known as protocol data units (PDUs), between themobile wireless communication device and the packet data network, apacket data protocol (PDP) context can be activated. As severaldifferent network elements can be involved in activating the PDP contextand because establishing the PDP context can require a user discernableamount of time, it can be preferable to maintain the PDP context evenafter the data connection becomes idle when there are no data packets totransmit. Radio resources in the radio access network, however, can bescarce, and the wireless communication network can release the radioresources allocated for the data connection during an idle period whilemaintaining the PDP context, thus placing the data connection in apreservation mode. When new data packets arrive at the mobile wirelesscommunication device for transmission to the public data network, newradio resources can then be allocated by the radio network subsystemover which to transport the new data packets.

During periods with high communication traffic in the radio accessnetwork, the radio network subsystem can choose to not allocate newradio resources to the mobile wireless communication device required forthe data connection. In this situation, the PDP context can remainactive, while the underlying data connection to support transport of thepackets can be unavailable. The mobile wireless communication device canthen accumulate unsent data packets in a pending data buffer andrepeatedly submit service requests for radio resources until the radioresources are allocated by the radio network subsystem. These repeatedservice requests can add unnecessary levels of signaling traffic to analready overloaded radio access network.

Thus there exists a need to modify radio resource signaling between themobile wireless communication device and the radio network subsystems ofthe wireless communication network during periods of radio accessnetwork congestion.

SUMMARY OF THE DESCRIBED EMBODIMENTS

The described embodiments relate generally to wireless mobilecommunications. More particularly, a method and apparatus is describedfor radio resource signaling during periods of radio access networkcongestion in a mobile wireless communication device.

In one embodiment, a method for radio link control in a mobile wirelessdevice can include at least the following steps. While a packet dataprotocol context between the mobile wireless device and while a wirelesscommunication network is active and no radio resources are allocated bythe wireless communication network on which to transmit data packets,the mobile wireless device executes the following steps repeatedly whenpending data packets exist in a pending data packet buffer. A retrycounter is set to a non-zero maximum integer retry value after receivingeach new data packet to transmit. A transceiver in the mobile wirelessdevice transmits a service request to establish radio resources betweenthe mobile wireless communication device and the wireless communicationnetwork when the retry counter is non-zero. After transmitting eachservice request to establish radio resources, the retry counter isdecremented.

In another embodiment, a method for radio link control in a mobilewireless device can include at least the following steps. For a datapacket in the pending data packet buffer, the mobile wireless devicetransmits a sequence of service requests to establish radio resourcesbetween the mobile wireless device and a wireless communication network.When no radio resources are allocated by the wireless communicationnetwork in response to the transmitted sequence of service requests, athreshold for the pending data packet buffer is set to a minimumthreshold value. All pending data packets above the set threshold andthe oldest pending data packet in the pending data packet buffer arediscarded. The transmitting and discarding steps are repeated until aradio resource is allocated by the wireless communication network or thepending data packet buffer is empty.

In yet another embodiment, a mobile wireless device is described. Themobile wireless device includes an application processor configured togenerate data packets and a transceiver configured to receive datapackets from the application processor and to transmit data packets to awireless communication network. The transceiver is configured to reset aretry counter to a non-zero maximum integer retry value after receivingeach new data packet to transmit. When no radio resources are allocatedby the wireless communication network on which to transmit the datapackets, and when the retry counter is non-zero, the transceiver isconfigured to transmit a service request to establish radio resourcesbetween the mobile wireless device and the wireless communicationnetwork. The transceiver is configured to decrement the retry counterafter transmitting each service request to establish radio resources.

In a further embodiment, a non-transitory computer readable medium forstoring non-transitory computer program code executable by a processorin a mobile wireless device includes at least the following.Non-transitory computer program code for transmitting a sequence ofservice requests to establish radio resources between the mobilewireless device and a wireless network after receiving a data packet ina pending data buffer. Non-transitory computer program code fordiscarding at least one pending data packet in the pending data packetbuffer when no radio resources are allocated in response to thetransmitted sequence of service requests. Non-transitory computerprogram code for repeating the transmitting and the discarding until aradio resource is allocated by the wireless network or the pending datapacket buffer is empty.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention and the advantages thereof may best be understood byreference to the following description taken in conjunction with theaccompanying drawings.

FIG. 1 illustrates a mobile wireless communication device located withina wireless cellular communication network.

FIG. 2 illustrates a hierarchical architecture for a wirelesscommunication network.

FIG. 3 illustrates a state transition diagram for a packet dataconnection of the mobile wireless communication device.

FIG. 4 illustrates components of the mobile wireless communicationdevice.

FIG. 5 illustrates connections of the mobile wireless communicationdevice to elements of the wireless communication network.

FIG. 6 illustrates a message sequence between the mobile wirelesscommunication device and the wireless communication network for asuccessful radio resource allocation.

FIG. 7 illustrates a message sequence between the mobile wirelesscommunication device and the wireless communication network for anunsuccessful radio resource allocation.

FIG. 8 illustrates another message sequence between the mobile wirelesscommunication device and the wireless communication network for anunsuccessful radio resource allocation.

FIG. 9 illustrates a repeated service request sequence between themobile wireless communication device and the wireless communicationnetwork for an unsuccessful radio resource allocation.

FIG. 10 illustrates a repeated service request sequence resulting from aseries of pending data packets in the mobile wireless communicationdevice.

FIG. 11 illustrates a service request sequence with limited repeatedservice requests for the sequence of pending data packets of FIG. 10.

FIG. 12 illustrates an alternative service request sequence withincreasingly delayed service requests for the sequence of pending datapackets of FIG. 10.

FIG. 13 illustrates a method to modify radio resource signaling betweenthe mobile wireless communication device and the radio network subsystemof the wireless communication network during radio access networkcongestion.

FIG. 14 illustrates a second method to modify radio resource signalingbetween the mobile wireless communication device and the radio networksubsystem of the wireless communication network during radio accessnetwork congestion.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

In the following description, numerous specific details are set forth toprovide a thorough understanding of the concepts underlying thedescribed embodiments. It will be apparent, however, to one skilled inthe art that the described embodiments may be practiced without some orall of these specific details. In other instances, well known processsteps have not been described in detail in order to avoid unnecessarilyobscuring the underlying concepts.

Mobile wireless communication devices can provide a multiplicity ofservices including both voice and data connections through wirelesscommunication networks. A data connection between a mobile wirelesscommunication device and an external data network, through a wirelesscommunication network, can be considered “active” when the mobilewireless communication device is “attached” to the wirelesscommunication network and when a “higher layer” packet data protocol(PDP) context is established. Radio access network resources, such asradio access bearers (RABs) can be used to transport packets, alsocalled protocol data units (PDUs), between the mobile wirelesscommunication device an radio network subsystems in a radio accessportion of the wireless communication network. Radio resources can beshared among multiple mobile wireless communication devices, and withlimited radio frequency bandwidth allocated for the radio access portionof the wireless communication network, the radio access bearers can bereleased from the mobile wireless communication device and can bere-allocated when the data connection becomes idle. The PDP context canremain active, even though radio resources can be not allocated. Thiscondition can be known as a “preservation mode.”

With the PDP context active, higher layer processes in the mobilewireless communication device can continue to send data packets to lowerlayer processes for transmission to the wireless communication network;however, without radio resources allocated by the wireless communicationnetwork, the data packets can accumulate in a pending data buffer. Eachnew data packet in the pending data buffer can trigger a service requestfrom the mobile wireless communication device to a radio networksubsystem (RNS) in the wireless communication network for radioresources. During periods of network congestion, e.g. when insufficientradio resources can be available for service requests from the mobilewireless communication device, radio resources can be not allocated. Themobile wireless communication device can then resubmit a service requestfor radio resources up to a maximum number of retries for each pendingpacket in the pending data buffer. A high number of pending higher layerdata packets can result in a large number of service request retries.Such a sequence of service requests can add a significant signaling loadon the radio access portion of the wireless communication network thatcan be already congested.

One or more different steps can be taken alone or in combination tolimit the number of service requests and lower the signaling load on theradio access network during a period of congestion in the radio accessportion of the wireless communication network. First, as requested radioresources can be used by the mobile wireless communication device totransmit any pending data packets, service requests for multiple pendingdata packets can be consolidated together, thereby limiting the totalnumber of service requests per pending data packet. Second, the numberof pending data packets can be limited by lowering thresholds on thepending data buffer, thereby discarding older data packets sooner, evenwhen no specific service request has been made for that pending datapacket. Third, the time between successive service requests can beincreased after each series of service request retries for a pendingdata packet in order to spread the signaling load over a longer timeperiod. In combination with limiting the number of pending data packetsin the pending data buffer, service requests can be both fewer in totaland less frequent in occurrence. The retry interval between servicerequests can be limited to a maximum number to ensure that when networkcongestion clears, the mobile wireless communication device can receivea response to a service request in a timely manner. Additional detailsof the method and apparatus to modify radio resource signaling betweenthe mobile wireless communication device and the radio network subsystemof the wireless communication network during radio access networkcongestion can is described in the following.

FIG. 1 illustrates a wireless communication network 100 of overlappingwireless communication cells to which a mobile wireless communicationdevice 106 can connect. Each wireless communication cell can cover ageographic area extending from a centralized radio network subsystem.The mobile wireless communication device 106 can receive communicationsignals from a number of different cells in the wireless communicationnetwork 100, each cell located at a different distance from the mobilewireless communication device 106. The mobile wireless communicationdevice 106 can be connected to a radio network subsystem 104 in aserving cell 102 and can be aware of neighbor cells in the wirelesscommunication network 100, such as radio network subsystem 108 inneighbor cell 110. The radio resources that connect the mobile wirelesscommunication device 106 to a cell can be limited and shared amongmultiple mobile wireless communication devices.

FIG. 2 illustrates a hybrid hierarchical architecture 200 for a wirelesscommunication network that includes both UMTS and GSM radio accessnetwork elements. A mobile wireless communication device 106 operatingin a GSM wireless communication network can be referred to as a mobilestation (MS) 204, while a mobile wireless communication device 106operating in a UMTS network can be referred to as user equipment (UE)202. (Wireless mobile communication devices 106 can include thecapability of connecting to multiple wireless communication networksthat use different wireless radio network technologies, such as to a GSMnetwork and to a UMTS network; thus the description that follows canalso apply to such “multi-network” devices as well as single networkdevices.) The MS 204 can connect to the GSM wireless communicationnetwork through a radio network subsystem known as a base stationsubsystem (BSS) 218. The BSS 218 can include a base transceiver station(BTS) 220 that transmits and receive radio frequency signals between theMS and the wireless communication network and a base station controller(BSC) that manages the communication between a core network 236 and theMS 204. In a GSM wireless communication network, an MS 204 can beconnected to one BSS at a time. As the MS 204 moves throughout the GSMwireless communication network, the BSC 222 can manage handover of theMS 204 to different BTS 220 located in different cells. The GSM radioaccess network BSS 218 connects to a centralized core network 236 thatprovides circuit switching and packet switching capabilities. The packetswitching capability can provide a General Packet Radio Service (GPRS)that transmits internet protocol (IP) packets between the MS 204 andexternal data networks.

The core network 236 can include a circuit switched domain 238 that cancarry voice traffic to and from an external public switched telephonenetwork (PSTN) and a packet switched domain 240 that can carry datatraffic to and from an external public data network (PDN). The circuitswitched domain 238 can include multiple mobile switching centers (MSC)228 that connect a mobile subscriber to other mobile subscribers or tosubscribers on other networks through gateway MSCs (GMSC) 230. Thepacket switched domain 240 can include multiple support nodes, referredto as serving GPRS support nodes (SGSN) 224, that route data trafficamong mobile subscribers and to other data sources and sinks in the PDN234 through one or more gateway GPRS support nodes (GGSN) 226. The corenetwork 236 can be commonly used by multiple radio link access networksubsystems that use different radio link technologies. As shown in FIG.2, both a UMTS terrestrial radio access network (UTRAN) 214 and a GSMBSS 218 can connect to the same core network 236.

The circuit switched domain 238 and the packet switched domain 240 ofthe core network 236 can each operate in parallel, and both domains canconnect to different radio access networks simultaneously. The UTRAN 214in the UMTS wireless access network can include multiple radio networksubsystems (RNS) 216. Each RNS 216 can include a “Node B” 206/210 thattransmits and receives radio frequency signals and a radio networkcontroller (RNC) 208/212 that manages communication between the “Node B”206/210 network elements and the core network 236. Unlike the MS 204 inthe GSM radio access network, the UE 202 can connect to more than oneradio network subsystem (RNS) 216 simultaneously. One RNS 216 caninclude a “serving” radio network controller (SRNC) 208 that maintainsthe logical connection between the UE 202 and the core network 236through a primary Node B 206. A second RNS 216 can include a “drift”radio network controller (DRNC) 208 that provides additional radio linkresources through a secondary Node B 210 that supplements the radio linkthrough the primary Node B 206.

A UMTS wireless communication network can use a wireless communicationradio link technology known as wideband code division multiple access(W-CDMA). W-CDMA transmissions can occupy a relatively wide bandwidthbased on a direct sequence spread spectrum modulation. Transmissionsbetween a UE 202 and an RNS 216 in a UMTS network can be modulated by aspreading code, and each UE 202 connected to the RNS 216 can use adifferent spreading code but transmit simultaneously using the samefrequency spectrum. Received signals can be demodulated by correlatingthem with a correctly matched de-spreading code. As the set of spreadingcodes used in W-CDMA can be mutually orthogonal, signals intended for aparticular UE can be separated from signals transmitted to other UE,even though all of the signals can overlap and use the same frequencyspectrum simultaneously. UMTS spread spectrum signals can occupy a wider5 MHz channel bandwidth compared with a narrower 200 kHz channelbandwidth used by GSM signals.

In order for the UE 202 to communication to the RNS 216, a radioresource, such as a radio access bearer (RAB) having a particularfrequency and spreading code, can be allocated by the RNS 216 inresponse to a service request from the UE 202. Radio resources can beallocated when requested and available and de-allocated when not used inorder to share the radio frequency spectrum among multiple UEs 202. Touse the GPRS capability of the wireless communication network, the UE202 can “attach” to the network and “activate” a packet data protocol(PDP) context. By attaching to the network, the UE 202 identifies itselfand the wireless communication network 100 confirms the location of theUE 202. Activating the PDP context can enable IP traffic transferthrough radio resources on an “air” interface between the UE 202 and theRNS 216. The UE 202 can obtain an IP address and can establish a logicalconnection with a quality of service (QoS) profile through the UMTSnetwork. A UE 202 can have multiple PDP contexts active simultaneously,and each PDP context can use a different RAB.

FIG. 3 illustrates a simple state diagram 300 for the UE 202. The UE 202can be in an inactive state 302, such as in a mobile management (MM)idle mode when UE 202 is not attached to a GPRS mobility managementsystem in the wireless communication network 100. The state of the UE202 can change to an active state 304 when a PDP context is activated(transition 306). The UE 202 can remain in the active state 304 evenwhen the PDP context is modified (transition 310), such as when a changeto a QoS profile associated with the PDP context occurs. While in theactive state 304, radio resources (e.g. radio access bearers) allocatedto the UE 202 can be released at the request of the serving radionetwork controller (SRNC) 208 in the RNS 216 with which the UE 202 isassociated. The PDP context can remain preserved by the core network(CN) 236 even when the associated RAB is released. In order tore-establish RABs for active PDP contexts that don't have associatedRABs, the UE 202 can send a service request message to the RNS 216asking for a new allocation of radio resources. Network congestion canresult in no RABs being allocated, however, the UE 202 can remain in theactive state. If the data connection is no longer required then the PDPcontext can be deactivated (transition 308), and the UE 302 can returnto an inactive state 302.

FIG. 4 illustrates typical components of the mobile wirelesscommunication device 106 such as the UE 202. An applications processor(AP) 402 can perform higher layer functions, such as maintaining an IPstack and requesting and releasing data connections. A transceiver(XCVR) 404 in the mobile wireless communication device 106 can transmitand receive lower layer packets that correspond to higher layersignaling and data packets through a radio “air” interface to the RNS216 in the wireless communication network 100.

FIG. 5 illustrates that a higher layer PDP context 504 can beestablished between the AP 402 in the mobile wireless communicationdevice 106 (equivalently the UE 202) and the core network 236 in thewireless communication network 100. This higher layer PDP context 504can be supported by a lower layer radio access bearer (RAB) 502 betweenthe transceiver 404 and the Node B 206 within the radio networksubsystem (RNS) 216. While the PDP context 504 can be active without anyradio resources (lower layer RABs 502) allocated for the radio accessportion of the wireless communication network 100, data packets cannotbe communicated between the AP 402 and the public data network (PDN) 234through the core network (CN) 236. An inactivity timer in the RNS 216can release the “costly” radio resources for other mobile wirelesscommunication devices to use when the data connection of the mobilewireless communication device 106 is idle, such as when the packet databuffer un the transceiver 404 is empty and a timer expires. The servingradio network controller (SRNC) 208 can send a signaling connectionrelease based on the inactivity timer or in response to a signalingconnection release indication from the mobile wireless communicationdevice 106. The PDP context 504 can require significant time to set up,as multiple network components can be involved in the PDP contextestablishment. Thus the PDP context 504 can remain active even when noRAB is assigned. When the XCVR 404 receives additional higher layerpackets from the AP 402 to transmit, the XCVR 404 can request radioresources on which to transport the new higher layer packets through anexchange of signaling messages as described next. Under normal networkload conditions, establishing new radio access bearers 502 can be fasterthan setting up an entirely new PDP context 504.

FIG. 6 illustrates a signaling message exchange 600 between the UE 202and the RNS 216 to request allocation of radio resources on which totransport pending data packets. A service request 602 can be sent fromthe UE 202 to the RNS 216. Note that this signaling message exchange 600can use signaling radio resources separate from those being requested tosupport data packet transport. The signaling radio resources can beshared by multiple UEs 202 and can provide only limited throughputcapability, and thus can be incapable of supporting substantial packetdata traffic. Several successive steps can occur to establish asignaling connection between the UE 202 and the RNS 216 includingestablishing a radio resource control (RRC) connection (step 604) withthe SRNC 208 in the RNS 218, followed by direct transfer messaging tothe CN 236 and a security mode procedure 608 to ensure authentication ofthe UE 202. After establishing the signaling connection, the RNS 216 canallocate 610 a radio access bearer (RAB), i.e. a radio resource, to theUE 202, and packet data transfer on the established data connection canoccur. The series of steps in FIG. 6 illustrate a successful request forradio resource allocation to the UE 202.

FIG. 7 illustrates an unsuccessful request for radio resource allocationfor the UE 202, where the RNS 216 establishes a signaling connection andthen releases the signaling connection by sending an RRC connectionrelease message 704. In this case no radio resources are allocated tothe UE 202, and the UE 202 can be unaware of a reason for the lack ofsuccess. In some cases the RNS 216 can send an optional service acceptmessage 702 after establishing the signaling connection and thensubsequently release the RRC connection 704 without actually allocatingradio resources. In either case, the UE 202 cannot send data packets onthe data connection as the radio access portion is not established.

FIG. 8 illustrates another unsuccessful radio resource service request,where the RNS 216 sends a service reject message 802 after establishingthe signaling connection. The service reject message 802 can include areason for the service reject. The RNS 216 can subsequently release thesignaling connection by sending an RRC connection release message 704.Again, no radio resources can be allocated to the UE 202. As the initialservice request can be precipitated by a pending data packet, which canremain unsent and therefore continue to be pending in a data buffer inthe UE 202, the UE 202 can generate repeated service requests as shownin FIG. 9 for a single pending packet 900. To simplify the diagram inFIG. 9, the steps that establish the signaling connection as shown inFIGS. 6-8 are not shown, but they can occur.

As illustrated in FIG. 9, a service request 902 can be followed by aservice failure 904 without any radio resources being allocated to theUE 202. FIGS. 6-8 illustrated representative radio resource servicerequest failures. The service failure response 904 from the RNS 216 canalso be not sent by the RNS or not received by the XCVR 404 in the UE202. Following each service request 902, the XCVR 404 in the UE 202 canwait a retry interval 906 before repeating the service request 902. Theretry interval 906 can be specified by the UE 202. Up to a maximumnumber of service requests can be retried before the XCVR 404 canabandon the service request procedure and discard the pending packet(step 908). In an exemplary embodiment, the retry interval 906 can beset between 10 and 30 seconds apart and the maximum number of retriescan be set for 2 to 4 for each pending packet 900. (Other non-zerointeger values for the retry interval 906 and maximum number of retriescan also be used.) A single pending packet 900 can result in asubstantial number of signaling messages exchanged between the XCVR 404and the RNS 216 during multiple attempts to have radio resourcesallocated to the UE 202 on which to transport the pending data packet.

The higher layer functions in the AP 402 of the UE 202 can be unaware ofthe lack of radio resource allocation and can continue to sendadditional data packets to the XCVR 404 for transmission, which canresult in a deep backlog of data packets. Each data packet 900 cangenerate a new set of signaling messages for a service request 902adding to the network congesting by overloading signaling radioresources. FIG. 10 illustrates four pending data packets 1002/1004/1006,and each data packet generates a maximum number of service request (SR)retries, with successive service requests spaced apart by a retryinterval 906. With a relatively deep data packet buffer in the XCVR 404,the AP 402 can send more than 50-100 data packets within one minute tothe XCVR 404 resulting in several hundred service requests beinggenerated by the XVCR 404 to the RNS 216. As a result an excessivelylarge number of signaling messages can be transmitted between the XCVR404 and the RNS 216 and can overload an already congested radio accessnetwork. As the PDP context can remain active when radio resources areunavailable, the higher layer applications in the AP 402 can be unawareof the radio resource blockage and can automatically retransmit datapackets to the XCVR 404 for transmission to the RNS 216 when noacknowledgements for the earlier data packets are received.

FIG. 11 illustrates a message sequence 1200 for a method with modifiedradio resource signaling between the XCVR 404 in the UE 202 and the RNS216 in the wireless communication network 100. A new set of servicerequests for each pending higher layer data packet can be not required,as the same radio resources for which allocation is sought can be usedfor all pending data packets. Rather than send a maximum number ofservice request retries for each pending data packet, a retry countercan be reset when each new higher layer data packet is received by theXCVR 404 from the AP 402. The maximum number of retries can then beapplied for all pending data packets rather than for each pending datapacket. As shown in FIG. 11, a first data packet 1002 can initiate afirst sequence of service requests. While the first sequence of servicerequests is ongoing, a second data packet 1004 can be received by theXCVR 404, and a new second sequence of service requests can start. Thenew second sequence of service requests can encompass both the newlyreceived second data packet 1004 and the first received data packet1002. The first sequence of service requests for the first packet 1002only can effectively end.

During the second sequence of service requests, a third data packet 1006can be received by the XCVR 404 triggering yet another new sequence ofservice requests that can apply to all three pending data packets. If noradio resources are allocated by the RNS 216, then the XCVR 404 candiscard all pending data packets after sending a sequence of servicerequests that includes a maximum number of service request retries. Thesequence of service requests at any time can apply to all currentlypending data packets.

The data packet buffer in the XCVR 404 can include a threshold thatlimits the total number of pending data packets so that the data packetbuffer can avoid an overflow. When the number of data packets in thedata buffer exceeds the threshold, then as new data packet are received,the oldest data packets can be discarded leaving room for the newer datapackets in the data buffer. A timestamp can also be associated with adata packet, and packets that remain pending longer than a timethreshold can be discarded.

FIG. 12 illustrates a second sequence 1200 for another method to modifyradio resource signaling between the XCVR 404 and the RNS 216. Aftersending a first set of service requests for a first pending data packet1002, a packet data control procedure (PDCP) in the UE 202 can change toa “stalled” state that can indicate that the radio access portion of thewireless communication network has not allocated radio resources inresponse to repeated service requests. While in the stalled state, theUE 202 can change the threshold for the pending data packet buffer inthe XCVR 404 to a smaller value, which can result in older data packetsbeing discarded earlier as the pending data packet buffer can overflowmore quickly. For example, if the packet data buffer is reduced to athreshold of only two data packets after changing to a stalled state,then when packet #3 arrives, pending packet #1 can be discarded due todata packet buffer overflow.

The retry interval between successive service requests for each set ofmultiple service requests can also increase after each multipleunsuccessful service request sequence. For example the retry intervalcan double after each set of service requests up to a maximum retryinterval value. As a representative embodiment, the default retryinterval can be 30 seconds with a default number of retries for each setof service requests set to 4 in a service request procedure. After thefirst four service request retries, the default retry interval canincrease to 60 seconds and then again to 120 seconds. For a next servicerequest procedure (not shown) the retry interval can max out at amaximum retry interval value of 180 seconds (less than double theprevious retry interval). The maximum retry interval value can be set toa level that minimizes overall signaling loads on the wirelesscommunication network, while still ensuring that recovery fromcongestion is not adversely affected.

When the RNS 216 allocates radio access bearers to the UE 202, the PDCPcan change back to a “normal” state from the “stalled” state, and thethreshold of the pending data packet buffer can be reset to a defaultvalue. The retry interval can also be reset to a default value. Inaddition to the two service request sequences shown in FIGS. 11 and 12,the XCVR 404 can notify the AP 402 when a stalled network conditionexists, as determined by the XCVR 404. After recognizing the stallednetwork condition, the AP 402 can choose to limit the frequency andnumber of data packets sent to the XCVR 404 until the stalled networkcondition subsides. Limiting the amount of data packets sent to the XCVR404 can limit the number of service requests generated by the XCVR 404in response to receiving the data packets, thereby decreasing thesignaling traffic on the radio access interface until network congestionimproves.

FIG. 13 illustrates a representative method 1300 to modify radioresource signaling to account for radio access network resourcecongestion. The method 1300 illustrated in FIG. 13 can correspond to thesequence 1100 shown in FIG. 11. In step 1302, the XCVR 404 in the UE 202can check whether any pending data packets exist, sent from a higherlayer process in the AP 402 of the UE 202 for transmission to thewireless communication network. When one or more pending packets existin the buffer, the XCVR 404 can determine in step 1304 if a new datapacket was received in the pending data packet buffer. Any new datapackets received can cause a retry counter to be reset to a defaultmaximum retry counter value in step 1306. If no new data packets werereceived, then the XCVR 404 can determine if the retry counter equalszero in step 1316, which can indicate that a maximum number of retrieshave occurred for the pending data packets. The method can terminate(and pending data packets can be discarded). If the maximum number ofservice request retries has not occurred, i.e. the retry counter is notzero, or after resetting the retry counter in step 1306 following thereceipt of a new data packet in step 1304, a service request can be sentin step 1308 by the XCVR 404 to the RNS 216 requesting radio resourceson which to transmit the pending data packets to the wirelesscommunication network. If a radio access bearer (RAB) is allocated instep 1310, then the method can end; however, if no radio resources areallocated then in step 1312 the retry counter can be decremented. Afterwaiting for a retry interval in step 1314, the XCVR 404 can return tocheck if a new data packet was received, thereby restarting the servicerequest retry procedure. The method 1300 shown in FIG. 13 can result inat least a maximum retry value number of retries for each pending datapacket. Thus all pending data packets can receive at least a minimumnumber of service request retries. Each service request for radioresources can apply to all pending data packets in the data buffer inthe XCVR 404.

FIG. 14 illustrates a second method 1400 to modify radio resourcesignaling when requesting radio resources when there radio accessnetwork resource congestion exists. In step 1402, the XCVR 404 in the UE202 can send up to a maximum retry value of service requests for radioaccess resources for a first pending data packet received from the AP402. If no radio access resources are allocated during step 1402 by theRNS 216, then the UE 202 can identify that the radio access network iscongested (i.e. in a stalled state). In the stalled state, the UE 202can lower the threshold on the pending data packet buffer in step 1404,thereby causing older pending data packets to be flushed from thepending data packet buffer more quickly. In step 1406 all pending datapackets above the lowered threshold can be discarded. The oldest pendingdata packet, which can correspond to the first pending data packet inthe first cycle through step 1406 or the most recent data packet forwhich a series of service requests has been made, can also be discardedeven if below the lowered threshold. A pending data packet can bediscarded after the maximum number of service request retries haveoccurred for the pending data packet. After discarding data packets, instep 1408, the XCVR 404 can determine if there are any remaining pendingdata packets in the data buffer. If the pending data packet buffer isempty, then the process can terminate.

If pending data packets still remain in the pending data packet buffer,then the XCVR 404 in step 1410 can increase the retry interval betweensuccessive service requests if the current retry interval is less than amaximum retry interval value. The XCVR 404, in step 1412, can then sendup to a maximum number of service requests, each successive servicerequest being spaced apart by the retry interval value. The set ofservice requests in step 1412 can apply to the oldest pending datapacket in the pending data packet buffer. In step 1414, the XCVR 404 candetermine if radio resources (i.e. radio access bearers) have beenallocated by the RNS 216. If no radio resources have been allocated,then in step 1406 the oldest pending data packet can be discarded andthe process can repeat. Once radio access bearers have been allocated orthe pending data packet buffer empties, in step 1416 the retry intervalcan be reset to a default retry interval value and the process can end.

In addition to the methods illustrated in FIGS. 13 and 14, other methodscan be used alone or in combination to lower the number of servicerequests for radio access resources. The lower layer baseband process inthe XCVR 404 can notify the higher layer process (e.g. IP stackmanagement) in the AP 402 of the UE 202 that a stalled state (i.e.congested network with inadequate radio access resources allocated)exists. The stalled state can be declared by the XCVR 404 after acertain number of service requests for radio resources have beensubmitted within a certain time period. The higher layer process in theAP 402 can then manage the number of data packets sent for transmissionas well as the time periods between successive data packets. Thismanagement of transmission by the higher layer process in the AP 402 canlower the number of data packets pending in the pending data packetbuffer of the XCVR 404, thereby lowering the number and frequency ofservice requests for radio resources. In a representative embodiment,the higher layer process can use a longer back off timer during astalled state to spread out successive TCP (Transmission ControlProtocol) SYN packets that seek to initiate a TCP connection. The higherlayer process can also wait longer periods between successive DNS(Domain Name Server) queries that look for IP addresses. The higherlayer process in the AP 402, however, should continue to send at leastsome data packets to the lower layer process in the XCVR 404 and shouldnot wait for an indication that the stalled condition has resolved. Asteady, if infrequent, stream of data packets can be required to ensurerepeated service requests will eventually result in an allocation ofradio resources from the RNS 216. Without any pending data packets, theXCVR 404 would not send any service requests, and without servicerequests, no radio resources would be allocated. This could result in adeadlocked condition as past service requests for radio resources by theUE 202 can essentially expire once the RRC connection is released by theRNS 216.

Various aspects of the described embodiments can be implemented bysoftware, hardware or a combination of hardware and software. Thedescribed embodiments can also be embodied as computer readable code ona computer readable medium for controlling manufacturing operations oras computer readable code on a computer readable medium for controllinga manufacturing line used to fabricate thermoplastic molded parts. Thecomputer readable medium is any data storage device that can store datawhich can thereafter be read by a computer system. Examples of thecomputer readable medium include read-only memory, random-access memory,CD-ROMs, DVDs, magnetic tape, optical data storage devices, and carrierwaves. The computer readable medium can also be distributed overnetwork-coupled computer systems so that the computer readable code isstored and executed in a distributed fashion.

The various aspects, embodiments, implementations or features of thedescribed embodiments can be used separately or in any combination. Theforegoing description, for purposes of explanation, used specificnomenclature to provide a thorough understanding of the invention.However, it will be apparent to one skilled in the art that the specificdetails are not required in order to practice the invention. Thus, theforegoing descriptions of specific embodiments of the present inventionare presented for purposes of illustration and description. They are notintended to be exhaustive or to limit the invention to the precise formsdisclosed. It will be apparent to one of ordinary skill in the art thatmany modifications and variations are possible in view of the aboveteachings.

The embodiments were chosen and described in order to best explain theprinciples of the invention and its practical applications, to therebyenable others skilled in the art to best utilize the invention andvarious embodiments with various modifications as are suited to theparticular use contemplated.

1-5. (canceled)
 6. A method for radio link control in a mobile wirelessdevice, the method comprising: in a mobile wireless device, transmittinga sequence of service requests to establish radio resources between themobile wireless device and a wireless communication network for a datapacket in a pending data packet buffer; when no radio resources areallocated in response to the transmitted sequence of service requests,setting a threshold for the pending data packet buffer to a minimumthreshold value; discarding all pending data packets above the setthreshold and the oldest pending data packet; and repeating thetransmitting and the discarding until a radio resource is allocated bythe wireless communication network or the pending data packet buffer isempty.
 7. The method as recited in claim 6, further comprising: when thepending data packet buffer is not empty, after the discarding,increasing a retry interval between successive service requests when theretry interval is less than a maximum retry interval value.
 8. Themethod as recited in claim 7, wherein increasing the retry intervaldoubles the retry interval up to the maximum retry interval value. 9.The method as recited in claim 8, wherein the allocated radio resourceis one or more radio access bearers.
 10. The method as recited in claim9, further comprising: after the radio resource is allocated, resettingthe retry interval to a default retry interval value. 11-24. (canceled)25. An apparatus for radio link control in a mobile wireless device, theapparatus comprising: means for transmitting a sequence of servicerequests to establish radio resources between the mobile wireless deviceand a wireless communication network for a data packet in a pending datapacket buffer; when no radio resources are allocated in response to thetransmitted sequence of service requests, means for setting a thresholdfor the pending data packet buffer to a minimum threshold value; meansfor discarding all pending data packets above the set threshold and anoldest pending data packet; and means for repeating the transmitting andthe discarding until a radio resource is allocated by the wirelesscommunication network or the pending data packet buffer is empty. 26.The apparatus as recited in claim 25, further comprising: means forincreasing a retry interval between successive service requests when theretry interval is less than a maximum retry interval value after thediscarding when the pending data packet buffer is not empty.
 27. Theapparatus as recited in claim 26, wherein increasing the retry intervaldoubles the retry interval up to the maximum retry interval value,wherein the allocated radio resource is one or more radio accessbearers, the apparatus further comprising: means for resetting the retryinterval to a default retry interval value after the radio resource isallocated.
 28. The method as recited in claim 6, further comprising: inthe mobile wireless device, when no radio resources are allocated inresponse to the transmitted sequence of service requests, notifying by alower layer process to a higher layer process in the mobile wirelessdevice that a stalled state exists, the higher layer process managingthe number of data packets sent for transmission and time periodsbetween successive data packets.
 29. The method as recited in claim 6,further comprising: resetting a retry counter to a non-zero maximuminteger retry value after receiving each new data packet to transmit;transmitting the sequence of service requests to establish radioresources between the mobile wireless device and the wirelesscommunication network when the retry counter is non-zero; decrementingthe retry counter after transmitting each service request to establishradio resources; and waiting a retry interval after decrementing theretry counter and before transmitting a subsequent service request. 30.The method as recited in claim 28, wherein the higher layer processdecreases the frequency of data packet transmission when the stalledstate exists.
 31. The method as recited in claim 28, wherein the higherlayer process maintains at least one data packet in the pending datapacket buffer when the stalled state exists.
 32. The method as recitedin claim 28, wherein the higher layer process lowers the number of datapackets pending in the pending data packet buffer when the stalled stateexists.
 33. The method as recited in claim 28, wherein the higher layerprocess increases a time interval between transmitted data packets thatseek to initiate a TCP connection through the wireless communicationnetwork when the stalled state exists.
 34. The method as recited inclaim 28, wherein the higher layer process increases a time intervalbetween successive DNS queries that look for IP addresses when thestalled state exists.
 35. The apparatus as recited in claim 25, furthercomprising: means for detecting a stalled condition when no radioresources are allocated by the wireless network during a pre-determinedtime interval; and means for restricting the number of data packetsreceived in the pending data packet buffer during the stalled condition.36. The apparatus as recited in claim 35, further comprising: means forlowering the frequency of transmission of service requests for radioresources during the stalled condition.
 37. The apparatus as recited inclaim 35, further comprising: means for decreasing the frequency of datapacket transmission during the stalled condition.
 38. The apparatus asrecited in claim 35, further comprising: means for maintaining at leastone data packet in the pending data packet buffer during the stalledcondition.
 39. The apparatus as recited in claim 35, further comprising:means for lowering the number of data packets pending in the pendingdata packet buffer during the stalled condition.
 40. The apparatus asrecited in claim 35, further comprising: means for increasing a timeinterval between transmitted data packets that seek to initiate a TCPconnection through the wireless communication network during the stalledcondition.
 41. The apparatus as recited in claim 35, further comprising:means for increasing a time interval between successive DNS queries thatlook for IP addresses transmitted by the apparatus during the stalledcondition.
 42. The apparatus as recited in claim 25, further comprising:means for resetting a retry counter to a non-zero maximum integer retryvalue after receiving each new data packet to transmit; means fortransmitting the sequence of service requests to establish radioresources between the mobile wireless device and the wirelesscommunication network when the retry counter is non-zero; means fordecrementing the retry counter after transmitting each service requestto establish radio resources; and means for waiting a retry intervalafter decrementing the retry counter and before transmitting asubsequent service request.